* {
 margin: 0;
 padding: 0;
 box-sizing: border-box;
}
html, body {
 height: 100%;
 background-image: url(../image/backpicture.jpg);
 background-repeat: no-repeat;
 background-position: center;
 background-size: cover;
}
.nav {
 width: 100%;
 height: 50px;
 background-color: rgb(51, 51, 51);
 color: white;
 display: flex;
 align-items: center;
 padding-left: 20px;
}
.container {
 height: calc(100% - 50px);
 width: 100%;
 display: flex;
 justify-content: center;
 align-items: center;
 background-color: rgba(255, 255, 255, 0.7);
}
